There has been some publicity saying that because people are not feeding bread to waterfowl some swans are starving to death.
Whilst as animal lovers we are saddened to hear that swans are starving there may well be more to why the swans are struggling other than people not giving bread. For example, the very dry summer may have drastically reduced the foods that waterfowl naturally forage for such as aquatic plants, insects etc. We certainly do promote supplementary feeding of waterfowl but the food should be nutritionally beneficial. Reputable wildlife Rescues such as Vale Wildlife Hospital have said that they do not promote feeding bread as they have seen first-hand the damage it causes birds.
So what is the problem with bread?
Bread offers little-to-no nutritional benefit but the birds will readily eat it when it is offered. The problem occurs as the calorific bread fills up the stomach so much that the bird will not forage for their normal natural diet that will give them all the vitamins and minerals they require. In particular, in young birds, a reliance on human supplied bread, and other junk food, discourages them to learn to forage for the natural foods they need to be healthy. In both cases this can lead to malnourishment and in severe cases in young birds to a condition called Angel Wing. Angel Wing is a condition in which the distal portion of wing appears flipped outward. It is caused by excessively rapid growth of feathers in relation to muscle development and as a result growing flight feathers cause excess stress and weight on carpal muscles. This in turn leads to the carpal portion of the wing to hang and twist outwards and prevents the bird from flying (Figure 1).
Possible causes of Angel Wing include:
- Over feeding &/or excessive calorie intake
- Genetic factors
- Excessive growth rate
- Manganese (or Vitamin E) and vitamin D3 deficiency
It is possible that the high calorie bread discourages natural foraging and thus can cause deficiencies in vitamins and minerals that then lead to Angel Wing in some birds. The condition can be reversed with proper feeding in young birds but once the bird is an adult it cannot be reversed. Although Angel Wing is not life threatening to the bird in a sheltered environment it would be unlikely to survive in the wild.
There can also be problems with bread that is left uneaten as this can attract predators that may be harmful to waterfowl. It can also, if left for long enough, grow mould that if the birds consequently eat can make them very ill. Another issue is one of uneaten bread adding to nutrient build up in the water, especially in closed water such as lakes and ponds. This excess of nutrients in the water can then lead to excess algae growth such as cyanobacteria (blue green algae) and harmful algal blooms that in severe cases depletes oxygen levels to the extent that aquatic plants and animals die out. This process of eutrophication is usually caused by the use of fertilisers and soil run off into water (and human sewage) that leads to high nitrogen and phosphorous levels in the water but there is an argument that bread may contribute to this albeit in a smaller way.
So what can I feed to waterfowl?
There is a place to have a commercial food that will allow families to carry on the pastime of feeding the waterfowl at parks, ponds and lakes etc. that will be nutritionally beneficial and not harm the birds. According to National Geographic safe food for waterfowl include cucumber, corn, peas, beans, broccoli, beets, squash, alfalfa, tomatoes, aubergine, peeled bananas, seeds, scrambled eggs, and rice. Foods to be avoided as they are harmful include avocados, onions, citrus fruits, chocolate, popcorn and, of course, bread. There are foods on the market for commercially kept waterfowl and the recommendation is that a commercial pellet for this instance should contain 14-17% Protein and 3-6% fat with added vitamins and minerals.
Brambles Pet and Wildlife Limited is a family owned company and the team have been involved in developing products for animal welfare since 1990. The Managing Director has a scientific background in Biological Sciences and we have combined our experience and expertise to formulate foods that are nutritionally beneficial to wild animals and ensure that they do not contain any added sugar, colours, or artificial flavours. Our Swan and Duck food conforms to recommended guidelines for nutritional requirements, is also suitable for geese, moorhens and coots, and, as it floats you can easily see when the birds have had sufficient.